||J.H. Lee, Y.J. Lee, Y.H.Han, D.G.Shin, S.Y.Kim and B.K. Jang, Microstructural Studies of Core/Rim Structure of Polycarbosilane-Derived SiC Consolidated by Spark Plasma Sintering, Ceramics International, 45, 12406-12410, 2019.04, Recently, attempts have been made to use silicon carbide (SiC) ceramics as a fuel compact in nuclear reactors.
However, the use of sintering additives in the conventional sintering of SiC leads to a coarse microstructure with
high porosity and large grains due to the low sinterability and the large amount of grain boundaries or a second
phase, deteriorating the mechanical properties, and hence limiting widespread industrial applications. In this
study, polycarbosilane (PCS) and spark plasma sintering (SPS) as the SiC precursor and sintering method, respectively,
were applied to overcome the low sinterability and the use of sintering additives. As the raw material,
amorphous PCS was prepared by pyrolysis at 1000 °C. To decrease the particle size, pyrolyzed PCS powder was
subjected to ball milling by using high-energy ball milling. The ball-milled amorphous PCS powder was sintered
by SPS. Sintering was carried out at different temperatures (i.e., 1700, 1800, and 1900 °C) and pressures (i.e., 40
and 80 MPa). After SPS, the core/rim structure of the sintered pellet was formed on account of the oxygen
originating from the native oxide layer and free carbon in the PCS powder as the raw materials. In the core/rim
structure comprising the core, as well as the intermediate and rim regions, the microstructure and chemistry of
each region exhibited marginal difference with respect to the free carbon and oxygen. The phase fraction of α-
SiC increased from the rim region to core region due to the discrepancy of actual loaded pressure on account of
friction with the wall surface. The existing carbon was verified to be graphitized carbon. Owing to the short
reaction time, graphitization did not completely proceed, and deficient graphitization led to graphitized carbon
as not graphite. The introduced oxygen changed to amorphous SiO2, which was applied to the sintering-additivelike
||B.K. Jang, Y. Sakka, N. Yamaguchi, H. Matsubara and H.T. Kim, Thermal Conductivity of EB-PVD ZrO2-4 mol% Y2O3 Films using the Laser Flash Method, Journal of Alloys and Compounds, 509, 3, 1045-1049, 2011.04.
||B.K.Jang, K. Tsuda, and Y. Sakka, Alignment of Carbon Nanofibers in the Al2O3 Matrix under a Magnetic Field, Materials Transactions, 52, 3, 572-575, 2011.03.
||H.O. Kim, B.K. Jang, D.S. Lim and Y. J. Oh, Characteristics of Lead-Free Transparent Dielectrics Contaminated with Moisture, Materials Chemistry and Physics, 129, 1-2, 134-137, 2011.02.
||Y.J. Oh, B.K. Jang, and H.O.Kim, Influence of Moisture Contamination of Lead-Free Transparent Dielectric Slurry for Tape Casting , Materials Letters, 65, 15-16, 2357-2360, 2011.11.
||K.H. Kwak, B.C. Shim, S.M. Lee, Y.S. Oh, H.T. Kim, B.K. Jang and S.W. Kim, Formation and Thermal Properties of Fluorite-Pyrochlore Dual Structure in La2(ZrxCe1-x)2O7 Oxide System, Materials Letters, 65, 19-20, 2937-2940, 2011.11.
||B.K. Jang, S.W. Kim, Y.S.Oh, H.T. Kim, Y. Sakka and H. Murakami, Influence of La2O3 Addition on Thermophysical Properties of ZrO2-4mol%Y2O3 Ceramics Fabricated by Spark Plasma Sintering, Journal of the Ceramic Society of Japan,, 119, 12, 929-932, 2011.12.
||S.W. Kim, B.K. Jang, Y.S. Oh, S.M. Lee, H.T. Kim, Y. Sakka, Thermal Conductivities of ZrB2-based Ceramics for Ultra-High Temperature Applications, Materials Intergration, 25, 2, 23-27, 2012.02.
||C.S. Kwon, S.M. Lee, Y.S. Oh, H.T. Kim, B.K. Jang, and S.W. Kim, Phase Evolution and Thermal Conductivities of (La1-xGdx)2Zr2O7 Oxides for Thermal Barrier Coatings, Journal of Korean Powder Metallurgy Institute, 19, 6, 429-434, 2012.06.
||B.K.Jang, J.G. Sun, S.W. Kim, Y.S. Oh and H.T. Kim, Characterization of the Thermal Conductivity of EB-PVD ZrO2- Y2O3 Coatings With a Pulsed Thermal Imaging Method, Surface and Coatings Technology, 207, 177-181, 2012.07.
||D.M.Kim, S.M.Lee, I.K.Kim, B.K.Jang, D.S. Lim and Y.S.Oh, Plasma Resistance of Y2O3 Nanofilms on Quartz with Different Interlayers Deposited by EB PVD, Journal of the Ceramic Society of Japan, 120, 11, 539-543, 2012.11.
||B.K. Jang, S.W. Kim, Y.S. Oh, H.T. Kim, Y. Sakka and H. Murakami, Effect of Gd2O3 on Thermal Conductivity of ZrO2-4mol%Y2O3 Ceramics Fabricated by Spark Plasma Sintering, Scripta Materialia, 69, 165-170, 2013.05.
||G. Suarez, B.K. Jang, E. Aglietti, and Y. Sakka, Fabrication of dense ZrO2/CNT composites: Influence of Bead-Milling Treatment, Metallurgical and Materials Transactions A, 44, 4374-4381, 2013.08.
||C.Y Park, Y.H Yang, S.W. Kim, S.M Lee, H.T Kim, D.S. Lim, B.K. Jang and Y.S. Oh, Thermal Durability of 4YSZ Thermal Barrier Coating Deposited by Electron Beam PVD, Journal of Korean Powder Metallurgy Institute, 20, 6, 460-466, 2013.06.
||K.S. Lee, B.K.Jang and Y.Sakka, Damage and Wear Resistance of Al2O3-CNT Nanocomposites Fabricated by Spark Plasma Sintering, Journal of the Ceramic Society of Japan, 121, 10, 867-872, 2013.10.
||X. H. Nguyen, I.K. Kim, B. K. Jang and Y.S. Oh, Effect of Carbon Content on the Tribological Behavior of TiCxN1-x Films Prepared by Arc-Vapor Deposition, Journal of the Ceramic Society of Japan, 121, 12, 961-967, 2013.12.
||W.J.Lee, B.K. Jang, D.S. Lim, Y.S. Oh, S.W. Kim, H.T. Kim, H. Araki, H. Murakami, S. Kuroda, Hot Corrosion Behavior of Plasma Sprayed 4 mol% Y2O3- ZrO2 Thermal Barrier Coatings with Volcanic Ash, Journal of the Korean Ceramic Society, 50, 6, 353-358, 2013.06.
||S.W. Kim, J.M. Chae, S.M. Lee, Y.S.Oh, H.T.Kim, B.K.Jang, Change in Microstructures and Physical Properties of ZrB2-SiC Ceramics Hot-Pressed with a Variety of SiC Sources, Ceramics International, 40, 2, 3477-3483, 2014.02, This paper reviewed briefly the thermal conductivities of ZrB2-based ultra-high temperature ceramics. As aerodynamic system, such as hypersonic plane, needs sharp leading edges to enhance vehicle maneuverability during atmosphere exit and re-entry, the thermal conductive properties of thermal protection system becomes more important. ZrB2 is one of the candidates for TPS application to ultra-high temperature environments over 2000C. One example of ZrB2-SiC ceramics with enhanced thermal conductivity was also introduced.
||D.Y. Kim, Y.H. Han, J.H.Lee, I.K. Kang, B.K.Jang and S.Y Kim, Characterization of Multi-walled Carbon Nanotube Reinforced Hydroxyapatite Composites Consolidated by Spark Plasma Sintering, BioMed Research International, 1-10, 2014.11, Pure HA and 1, 3, 5, and 10 vol% multiwalled carbon nanotube- (MWNT-) reinforced hydroxyapatite (HA) were consolidated using a spark plasma sintering (SPS) technique.The relative density of pure HA increased with increasing sintering temperature, but that of theMWNT/HA composite reached almost full density at 900∘C, and then decreased with further increases in sintering temperature. The relative density of the MWNT/HA composites increased with increasing MWNT content due to the excellent thermal conductivity of MWNTs. The grain size of MWNT/HA composites decreased with increasing MWNT content and increased with increasing sintering temperature..
||S. Rawati, B.K. Jang, P. Mohapatra and K. Balani, Toughening by Carbon Nanotube Reinforcement in 3mol% Yttria-Stabilized Zirconia, Materials Science and Technology of Japan, 51, 2, 23-27, 2014.02.
||I.S. Han, D.W. Seo, S.Y. Kim, S.K. Woo, H.J. Lee and B.K. Jang, Performance-Properties and Fabrication of the Reaction Sintered Si/SiC Honeycomb Materials for Solar Absorber Application, J Journal of the Ceramic Society of Japan, 122, 6, 502-508, 2014.06, Reaction sintered Si/SiC composite was fabricated to apply to a solar absorber and the fabricated material was evaluated on its basic properties and performance. SiC and carbon black were mixed to shape a honeycomb with a multi-channel via vacuum extrusion process. The Si/SiC honeycomb material was also fabricated with less than 5% of pores by molten silicon infiltration in vacuum. The sintered density and porosity of the fabricated material, and the 3-point bending strength at room temperature and high temperature (11001300°C) were measured and the thermal conductivity at room temperature and 1100°C were also analyzed..
||S.W. Myoung, Z. Lu, Y.G. Jung, B. K. Jang, Y.S. Yoo, S.M. Seo, B.G. Choi and C. Y. Jo, Effect of Plasma Pre-treatment on Thermal Eurability of Thermal Barrier Coatings in Cyclic Thermal Exposure, Advances in Materials Science and Engineering, 1-8, 2014.06, Plasma pretreatment on the top and bond coats was performed and its influence on the thermal durability of thermal barrier coating (TBC) system was investigated through cyclic thermal exposure. Two types of bond coat were prepared by different methods, namely, air plasma spray (APS) and high-velocity oxy-fuel (HVOF), and two kinds of feedstock powder were employed for preparing the top coat in APS process. The better thermal durability was achieved in the vertically cracked TBC with the surface modified bond coat or with the bond coat prepared by APS process. .
||C.Y. Park, S.M. Lee, S.W. Kim, H.T. Kim, B.K.Jang, Y.S. Oh, Effects of N2/Ar Gas Ratio on Phase Formation and Tribology of Ti-Si-N Composite Coatings Prepared by Hybrid PVD, Journal of the Ceramic Society of Japan, 122, 8, 638-641, 2014.08, TiSiN hard coatings have been fabricated at different N2/Ar gas ratio (N2:Ar = 1:1, 1:2, or 1:3) sputtering conditions by the hybrid Physical Vapor Deposition (PVD) method, which consists of sputtering and arc ion plating (AIP). The pure silicon and titanium targets were selected for reactive sputtering and the AIP process, respectively. Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis has shown that the Ti/Si ratio increased as the Ar gas flow rate increased. Moreover, it found that the main growth plane of TiSiN film was changed from (111) plane to (220) plane with increasing Ar gas flow from the results of X-ray diffraction (XRD) analysis..
||C.Y. Park, Y.H. Yang, S.W. Kim, S.M. Lee, H.T. Kim, B.K. Jang, D.S. Lim, and Y.S. Oh, Effect of La2O3 Addition on Interface Chemistry Between 4YSZ Top Layer and Ni Based Alloy Bond Coat in Thermal Barrier Coating by EB PVD, J. Nanoscience and Nanotechnology, 14, 11, 8659-8664, 2014.11, The effect of a 5 mol% La2O3 addition on the forming behavior and compositional variation at interface
between a 4 mol% Yttria (Y2O3) stabilized ZrO2 (4YSZ) top coat and bond coat (NiCrAlY)
as a thermal barrier coating (TBC) has been investigated. Top coats were deposited by electron
beam physical vapor deposition (EB PVD) onto a super alloy (Ni Cr Co Al) substrate without
pre-oxidation of the bond coat. Top coats are found to consist of dense columnar grains with a
thin interdiffusion layer between metallic bond coat..
||S.W. Myoung, Z. Lu, Y.G. Jung, B.K. Jang, U.G Paik, Control of Bond Coat Microstructure in HVOF Process for Thermal Barrier Coatings, Surface & Coatings Technology, 260, 63-67, 2014.08, The microstructure of bond coat was optimized by controlling coating parameters, such as spray distances, the
gas flow ratio of air/oxygen/hydrogen, gun speed, and step distance, in high-velocity oxy-fuel process, and the
effects of coating parameters on the microstructure and thermomechanical properties were investigated.
When the spray distance to the substrate shortened, the microstructure became dense and the hardness values
were increased. As the amount of hydrogen increased in the fixed gas flow ratio, defects such as global pores and
oxides were increased and the hardness valueswere decreased, showing a similar trend in oxygen..
||K.Seya, B.K. Jang and S. Ueno, Preparation of Environmental Barrier Coating with Al2O3-HfO2 Eutectic Structure by Optical Zone Melting Method, Materials Science and Technology of Japan, 52, 31-35, 2015.10.
||K.Seya, B.K. Jang and S. Ueno, Microstructure Formation of Al2O3-HfO2 Eutectic, Journal of the Ceramic Society of Japan, 123, 5, 433-436, 2015.05, The microstructure formation of Al2O3HfO2 eutectic prepared by unidirectional solidification and rapid solidification was examined. The microstructure of the Al2O3HfO2 eutectic samples showed lamellar structure and the relationship between the inter-lamellar spacing and solidification rate R can be expressed by 2R=constant. A small amount of tetragonal HfO2 phase exists in the sample prepared by rapid solidification. Only monoclinic HfO2 phase can be found in the eutectic samples prepared by unidirectional solidification. A tensile stress was induced in Al2O3 phase during the cooling step due to the transformation of HfO2 from tetragonal to monoclinic phase..
||I.Bajpai, D.Y. Kim, Y.H. Han, B.K.Jang and S.Y Kim, Directional Property Evaluation of Spark Plasma Sintered GNPs-Reinforced Hydroxyapatite Composite, Materials Letters, 158, 62-65, 2015.09, Graphene nanoplatelets(GNPs)-reinforcedhydroxyapatitecompositeswereanalyzedintwodirections
||K.Seya, S. Ueno and B.K. Jang, Formation of Al2O3-HfO2 Eutectic EBC Film on Silicon Carbide Substrate, Journal of Nanomaterials, 1-8, 2015.08, The formation mechanism of Al2O3-HfO2 eutectic structure, the preparation method, and the formation mechanism of the eutectic EBC layer on the silicon carbide substrate are summarized. Al2O3-HfO2 eutectic EBC film is prepared by optical zone melting method on the silicon carbide substrate. At high temperature, a small amount of silicon carbide decomposed into silicon and carbon. The components of Al2O3 and HfO2 in molten phase also react with the free carbon. The Al2O3 phase reacts with free carbon and vapor species of AlO phase is formed. The composition of the molten phase becomes HfO2 rich from the eutectic composition. HfO2 phase also reacts with the free carbon and HfC phase is formed on the silicon carbide substrate; then a high density intermediate layer is formed..
||S.W. Kim, J.M.Chae, S.M. Lee, Y.S. Oh, H.T. Kim and B.K.Jang, Transmission Electron Microscopy Investigation of Hot-pressed ZrB2-SiC with B4C additive, Journal of the Korean Ceramic Society, 52, 6, 462-466, 2015.05.
||B.K.Jang, J.G. Sun, S.W. Kim, Y.S. Oh, S.M. Lee and H.T. Kim, Thermal Conductivity of ZrO2-4mol%Y2O3 Thin Coatings by Pulsed Thermal Imaging Method, Surface and Coatings Technology, 284, 57-62, 2015.05, Thin ZrO2-4 mol% Y2O3 coatings were deposited onto ZrO2 substrates by electron beam-physical vapor deposition.
The coated samples revealed a feather-like columnar microstructure. The main phase of the ZrO2-4 mol%
Y2O3 coatings was the tetragonal phase. To evaluate the influence of the coating's thickness on the thermal conductivity
of thin ZrO2-4 mol% Y2O3 coatings, the pulsed thermal imaging method was employed to obtain the
thermal conductivity of the coating layer in the two-layer (coating and substrate) samples with thickness between
56 and 337 μm. The thermal conductivity of the coating layer was successfully evaluated and compared
well with those obtained by the laser flash method for similar coatings. The thermal conductivity of coatings
shows an increasing tendency with an increase in the coating's thickness..
||C.S.Kwon, S.M. Lee, Y.S. Oh, H.T. Kim B.K.Jang and S.W. Kim, Fabrication and Characterization of La2Zr2O7/YSZ Double-Ceramic-Layer Thermal Barrier Coatings Fabricated by Suspension Plasma Spray, Journal of the Korean Institute of Surface Engineering, 48, 6, 315-321, 2015.06.
||C.S.Kwon, S.M. Lee, Y.S. Oh, H.T. Kim B.K.Jang and S.W. Kim, Fabrication and Characterization of Ceramics and Thermal Barrier Coatings of Lanthanum Zirconate with Reduced Rare-earth Contents in the La2O3-ZrO2 System, Journal of Korean Powder Metallurgy Institute, 22, 6, 413-419, 2015.06.
||K.Seya, S. Ueno, T. Nishimura and B.K. Jang, Consideration of the Formation Mechanism of an Al2O3-HfO2 Eutectic Film on a SiC Substrate, Journal of the Korean Physical Society, 68, 1, 73-76, 2016.01.
||S. Ueno, K.Seya, Y. Furukawa., T. Nishimura, B.K. Jang, Fabrication of Oxide Eutectic Environmental Barrier Coating without Boundary Glassy Phase, Materials Science and Technology of Japan, 53, 2, 30-33, 2016.08.
||S. Ueno, Y. Suzuki, Y. Furukawa, T. Tada, N. Kannno and B.K. Jang, Crystallization of Glass with Y2Si2O7-Mullite Eutectic Composition, Journal of the Ceramic Society of Japan, 124, 8, 796-799, 2016.08, In this paper, the crystallization of the glass with Y2Si2O7-mullite eutectic composition was examined. A dendrite Y2Si2O7 crystalline grows from the surface of the glass bulk at 1302 K. A competitive growth of Y2Si2O7 phase and mullite phase occurs at 1430 K. The activation energy for the competitive growth can be estimated to 329 kJ/mol. The activation energy for the crystallization of hypoeutectic and hypereutectic composition increases with increasing the amount of the primary phase..
||S. Ueno, T. Tada, Y. Suzuki, J. Nozawa, B.K. Jang and T. Sekino, Crystallization and Microstructure Formation of Glass with Y2Si2O7-Mullite Eutectic Composition, Ceramics International, 42, 13601-13604, 2016.07, The crystallization and microstructure formation of glass with a Y2Si2O7-mullite eutectic composition were examined. A crystallization of Y2Si2O7 and the mullite phase due to phase separation occurred at 1174°C, and a well-developed Y2Si2O7 facet crystal was formed. This sample was melted down and solidified via heat treatment at 1250 °C and 1300 °C, temperatures below the melting point of a Y2Si2O7 mullite eutectic..
||K.J. Kim, S.H. Jang, Y.W.Kim, B.K. Jang and T. Nishimura, Conductive SiC Ceramics Fabricated by Spark Plasma Sintering, Cearmics International, 42, 17892-17896, 2016.07, Recently, the development of electrically conductive SiC have received a large attention because the electrical conductivity of SiC can be improved by microstructural control due to incorporation of electrical dopants (ex, CNTs, graphene), sintering atmosphere and sintering additives. In present work, we examined the thermal-electrical properties of SiC ceramics. For micorstructural control of SiC ceramics, Y2O3 was used for sintering additive and addition of Y2O3 is the range of 0.05~0.005wt%. Sintered SiC samples were fabricated by spark plasma sintering (SPS) at 1950C, pressure of 60MPa in N2 atmosphere. Thermal conductivity of SiC was increased with increasing of Y2O3 addition. The effect of Y2O3 on mechanical, electrical properties of SiC was investigated..
||F.J. Feng, B.K. Jang J.Y. Park and K. S. Lee, Effect of Yb2SiO5 addition on the physical and mechanical properties of sintered mullite ceramic as an environmental barrier coating material, Ceramics International, 42, 15203-15208, 2016.07, In this tudy, ytterbium monosilicate(Yb2SiO5)-added sintered mullite ceramics are prepared as candidate materials for environmental barrier coatings(EBCs).The effect of adding Y b2SiO5 on the physical and mechanical properties of the sintered mullite ceramics is investigated. TheYb2O3–SiO2–Al2O3 ternary phase diagram indicates that adding Yb2SiO5 to the mullite goes beyond imply mixing; Instead, liquid sintering occurs. Therefore, when we add Yb2SiO5 to the mullite, the sintered body possesses a denser microstructure and faster densification rate than does pure mullite..
||B.K. Jang, F.J. Feng, K.S. Lee, E. Garcia, A. Nistal, N.Nagashima, S.W. Kim, Y.S. Oh and H.T. Kim, Thermal behavior and mechanical properties of Y2SiO5 environmental barrier coatings after isothermal heat treatment, Surface & Coatings Technology, 308, 24-30, 2016.06, Y2SiO5 coatings are deposited by a flame-spray technique as protection layer on SiC substrates to prevent oxidation
and steam corrosion. In this research, Y2SiO5 coatings were isothermally heat treated at different temperatures
and different exposure times in a laboratory environment. The thermal behaviors such as phase
transformation, microstructural change and thermally grown oxide (TGO) formation have been examined by
XRD, SEM, and EDS analysis. Different modes of TGO growth behavior were found at different temperatures. In
addition, the mechanical properties were evaluated by a Martens hardness tester. The results show that the
change of microstructure and composition is not too critical, but higher temperatures and longer heating times
do lead to the formation of Y2SiO5 crystalline phases and a β-Y2O3 phase. Thus, the isothermal heat treatment
improves the hardness and elastic modulus of Y2SiO5 coatings..
||B.K. Jang, S.W. Kim, Y.S. Oh, S.M. Lee and H.T. Kim, Degradation of EB-PVD ZrO2-4mol%Y2O3 thermal barrier coatings by volcanic ash deposits, Journal of the Ceramic Society of Japan, 124, 9, 886-889, 2016.09, This work describes the degradation of ZrO24 mol%Y2O3 (YSZ) coatings obtained by EB-PVD. YSZ coatings were exposed at 1200°C for 10 min~50hr by isothermal heat treatment in the presence of an erosive impurity of volcanic ash. At the interface between the YSZ coatings and volcanic ash, the coatings were partially dissolved in the volcanic ash, resulting in the degradation of coatings by the formation of the reacted region. A ZrSiO4 or glassy phase is formed by the chemical reaction between YSZ coatings and volcanic ash at 1200°C..
||Y. Furukawa, T. Yanai, K. Seya, B.K. Jang and S. Ueno, Chemical Reactions between SiC and ZrO2 at Ultra-high Temperatures and Formation of EBC Layer by Solidification Process, Materials Science and Technology of Japan, 2016.05.
||S Ueno, K. Seya and B.K.Jang, Fabrication of EBC System with Oxide Eutectic Structure, Ceramic Transactions, 256, 65-72, 2016.06.
||S.J.Kim, S.M.Lee, Y.S. Oh and H.T. Kim, B.K. Jang and S.W. Kim, Characteristics of Bulk and Coating in Gd2-xZr2+xO7+0.5x(x= 0.0, 0.5, 1.0) System for Thermal Barrier Coatings, Journal of the Korean Ceramic Society, 53, 6, 652-658, 2016.05.
||S.J.Kim, S.M. Lee, Y.S. Oh, H.T. Kim B.K.Jang and S.W. Kim, Phase Formation and Thermal Diffusivity of Thermal Barrier Coatings of La₂Zr₂O7, (La0.5Gd0.5)₂Zr₂O7, Gd₂Zr₂O7 Fabricated by Suspension Plasma Spray, Journal of the Korean Institute of Surface Engineering, 49, 6, 604-611, 2016.06.
||T, Matsudaira, B.K. Jang, S.D. Kim and S.K. Woo, Effect of Water Vapor on Static Fatigue Behavior of Ni-YSZ Ceramics, Journal of the Ceramic Society of Japan, 125, 5, 1-3, 2017.05, The effect of water vapor on the mechanical properties of a porous nickel/yttria-stabilized zirconia (Ni-YSZ) composite (volume ratio of Ni:YSZ = 40:60) was evaluated at 850°C, a typical operating temperature of a reversible solid oxide cell. Both the flexural strength and static fatigue limit of Ni-YSZ obtained from the static fatigue lifetime under a wet atmosphere (containing 4% H2O) were lower than those under a dry atmosphere. This can be explained by absorption of H2O molecules into YSZ particles, resulting in accelerated crack growth. The fatigue limit of Ni-YSZ was confirmed to be extremely low, corresponding to almost one-third of the flexural strength..
||B.K. Jang, F.J. Feng, K. Suzuta, H. Tanaka,Y. Matsushita, K.S. Lee, and S. Ueno, Corrosion Behavior of Volcanic Ash and CMAS on Yb2SiO5 Environmental Barrier Coatings, Journal of the Ceramic Society of Japan, 2017.04, High-temperature corrosion behavior of volcanic ash and artificial calcium-magnesium-aluminosilicate (CMAS) on sintered ytterbium monosilicate (Yb2SiO5), and the corrosion resistance of Yb2SiO5 as an environmental barrier coating (EBC), are investigated. Dense sintered Yb2SiO5 specimens were prepared using the spark plasma sintering method at 1400 °C for 10 min. These specimens were subjected to a hot corrosive environment of molten Iceland volcanic ash and CMAS at 1400 °C for 2 hr, 12 hr, and 48 hr. Different corrosion phenomena, i.e., continuous reaction with CMAS and weak reaction with the volcanic ash, were observed. From the results of in-situ high temperature XRD measurement and SEM-EDS studies, Yb2SiO5 exhibits excellent resistance to volcanic ash but lacks resistance to CMAS attack..
||B.K. Jang, F.J. Feng, K.Suzuta, H. Tanaka, Y. Matsushita, K.S.Lee, S.W. Kim, Y.S. Oh and H.T. Kim, Corrosion behavior of volcanic ash on sintered mullite for environmental barrier coatings, Ceramics International, 43, 2, 1880-1886, 2017.06, The high-temperature corrosion behavior of volcanic ash(VA) in attacking sintered mullite was investigated, and
the corrosion resistibility of mullite environmental barrier coatings (EBCs) to VA was predicted. Sintered
mullite specimens were prepared by using the spark plasma sintering method. These specimens were subjected
to a hot corrosive environment—molten Icelandic VA at 1400 °C—for three different duration times (2, 12, and
48 h). The microstructure and phase of the specimens were analyzed by using a scanning electron microscope
equipped with an accessory system for energy dispersive spectroscopy and X-ray diffraction. In addition, in-situ
high-temperature X-ray diffraction was carried out to identify the dynamics of phase evaluation in the volcanic
ash and mullite mixture powders. Results show that a reaction layer was generated and continuously dissolved
into the melted volcanic ash. The primary incursive component is iron; however, a minimal amount of sodium
plays a more important role in disintegrating sintered mullite..
||Y.S. Oh, S.W. Kim, S.M. Lee, H.T. Kim and B.K. Jang, Effect of the Coating Parameters on the Microstructure, Hardness and Thermal Conductivity of 8 wt% Y2O3-ZrO2 Thermal Barrier Coatings by Atmospheric Plasma Spray, Materials Science and Technology of Japan, 54, 4, 8-12, 2017.08.
||H.Elyas, T.W.Kim, B.K.Jang and K.S.Lee, Damage and Wear Resistance of Al2O3-SiC Microcomposites with Hard and Elastic Properties, Journal of the Ceramic Society of Japan, 126, 1, 21-26, 2018.04, Al2O3SiC
composites with different SiC contents of 010
wt% were fabricated and the effects on damage and
wear resistance investigated. The composites were fabricated using spark plasma sintering at 1600°C in a partial
vacuum (80MPa). Hertzian indentation evaluations using a spherical indenter indicated that the hardness of the
composite is improved by SiC addition. Wear resistance evaluated using the ball-on-disk method showed
enhanced wear resistance for the composites, even when SiC addition was less than 2wt%. Thus, Al2O3 ceramics
exhibited significantly improved damage and wear resistance, even though SiC addition was as small as 2 wt%..
||.J.Lee, J.H. Lee, D.G.Shin, A. Noviyanto, H.M.Lee, T. Nishimura, B.K. Jang, W.T.Kwon, Y.H.Kim, S.Y.Kim, J.H.Lee, Y.H.Han, Phase Transformation on Spark Plasma Sintered Dense Polycarbosilane-derived SiC without Additive, Scripta Materialia, 143, 15, 188-190, 2018.04, SiC was sintered by spark plasma sintering (SPS) using polycarbosilane (PCS), and the effects of pressure on the
sintering behavior of SiC during SPS were investigated. The pressure conditions were set as 40 and 80 MPa, and
pyrolyzed PCS was used to induce reactive sintering during heat treatment such as pyrolysis, crystallization, and
crystal growth. According to the results, a high pressure accelerated the reactions in samples and resulted in a
high-density body consisting of small-sized grains; however, it induced a phase transition to the α phase,
which is stable at high temperatures..
||N. Kanno, B.K. Jang and S. Ueno, Crystallization of a Glass with Yb2Si2O7-Al6Si2O13 Eutectic Composition and Eutectic Microstructure Formation, Materials Science and Technology of Japan, 2017.08.
||B.K. Jang, S.W. Kim, Y.S. Oh and H.T. Kim, High Temperature Corrosion of ZrO2-4mol%Y2O3 Thermal Barrier Coatings with Volcanic Ash, Materials Science and Technology of Japan, 54, 4, 22-25, 2017.08.
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